The aim of the project is to study visual transduction and synaptic integration in the vertebrate retina, using single cell recording techniques. Transduction will be examined in toad rods by measuring the membrane current of single rod outer segments. We hope to define the way in which single photon effects occurring at various positions and temporal separations interact with one another in the outer segment. The site of origin of the electrical dark noise will be examined and its quantitative properties analyzed to obtain information about the light-sensitive ionic channels in the outer segment membrane. Information transfer from rods to retinal ganglion cells will be studied in double electrode experiments to define the minimal electrical signal detectable by the retinal pathways and the role of synaptic filtering and receptor dark noise in setting the detectability of signals. Additional experiments on interactions will address the amplification factor for synaptc transfer at a well defined synaptic junction and the mechanism of directional motion sensitivity.